Feb 5 2008
NEC Corporation today announced that it has succeeded in the development of a new data-recovering large scale integrated circuit (LSI), which will enable substantial improvement in data-receiving performance of 40 gigabits per second (Gbps) and beyond optical fiber transmission systems.
This is the world's first chip to incorporate an adaptive data-decision control scheme and novel 40Gbps signal-waveform monitor circuit technology. These new features together achieve correct recovery of digital information from input data signal waveforms with complex distortion caused by impairments such as optical fiber dispersion or receiver-circuit speed limitation. The new LSI is also expected to contribute to the realization of future 100Gbps optical transmission systems.
Rapid proliferation of the internet worldwide is generating increasingly high demand for telecommunication networks boasting higher data transmission capacity. Higher capacity also will be vital to the realization of next-generation networks (NGNs) that facilitate multiple services on a single platform. To meet these demands, backbone optical fiber networks have been forced to enlarge their data rate from the 10 Gbps of conventional systems to 40 Gbps.
However, at a higher data rate, the signal waveform suffers from increased distortion arising from optical fiber dispersion and speed limitation in electrical circuits. Moreover, long-distance optical fiber transmissions of 40Gbps and beyond generate even more complex waveform distortion, which rapidly and randomly varies over time. Therefore, it is becoming exceedingly difficult to correctly recover data from input signals.
NEC has succeeded in solving this issue through the implementation of a new signal-recovering technique into an LSI, whose features include:
- A 40Gbps high-speed, high-precision signal-waveform monitor circuit to detect complex and time-varying signal distortion.
- An adaptive data-recovering scheme that continuously optimizes the decision point in distorted signal waveform through feedback from the waveform monitor circuit.
These features combine to achieve precise and stable recovery of data, even from input signals with highly complex and time-varying distortion. Moreover, the high data-recovery performance of the newly developed LSI is not affected by variation in the operating condition. This enables maintenance-free operation, which will achieve a reduction in the cost of 40 Gbps transmission systems.
NEC will continue to develop this research toward realization of high-performance and low-cost 40Gbps and beyond data-link systems. The results of this research will be presented on February 5 at the International Solid-State Circuit Conference (ISSCC) 2008, February 3 to 7 in San Francisco, California, U.S.A.